Rotor of mercury bath electricity meters



Y Feb. 26, 1929.

1,703,727 S. Z. DE FERRANTI 'Ro'ron 'oF MERCURY Bmx ELECTRICITY uETsRs Filed April 14, 1925 41 b F m' 1% MQ@ Ni Fakir-Q 2 de Felpa/ML; 3 ma Patented Feb. 26, 1929.

i UNITED STATES PATENT OFFICE. f

SEBASTIAN ZIANI DE FERRANTI, OF HOLLINWOOD, ENGLAND, ASSIGNOR T0 FERRANTI, LIMITED, OF HOLLINWOOD, ENGLAND.

ROTOR or MERCURY BAT Application filed April 14, 1925, semi No.Y

This invention relates to disc rotors of mercury bath electricity meters, which rotors are protected from amalgamation with mer? cury by a. metallic coating applied thereto.

It is necessary to remove air from beneath the rotor disc after the latter is immersed in the mercury within the bath and it is usual to drill or punch a plurality of holes near the spindle collet to enable this air to escape or to be withdrawn. j

I find it necessary as fa r as possible to guard against the possibility of failure of the protective coating due to the presencefof these holes and due to the usual methods of fixing the spindle collet.

Accordingly I form in the disc a single central aperture in lieufof the plurality of holes adjacent the spindle collet, this aperture being rounded at both ends so as to produce an inner periphery which is convex in any plane containing the longitudinal axis of the disc and I form a collet as a spider which is suitably shaped in order not to damage the coating within the central hole.

Again, I find it desirable slightly'to taper the dise bot-h near its outer periphery and near its central hole so that when the dise is subjected to a hammering or pressing (in order to harden and render it compact) the edges are left intact, the coating thus being unimpaired.

Referring to the accompanying diagrammatic drawings Figures l and 2 represent cross-sectional views of a disc rotor in two stages of treatnientin accordance with the present invention;

Figure S is a xsection on' the line A+A'of Figure l and represents the discnimlnted on the spindle in a convenient marmer in accordance with the present invention;

Figure 4 is a plan view corresponding to Figure 3, and

Figure 5 is a sectional view through B-B of Figure 4.

In carrying the invention into effect according to one example in accordance With the present invention as illustrated in Figures l-, I provide a metal disc a, say of copper, with a central aperture and annular tapered surfaces b b, c c adjacent'this aperture and H ELECTRICITY METERS.

23,120, and 1n Great Britain June 19, 1924.

adjacent the periphery respectively. This let comprises conveniently a spider (l with four spokes, this being inserted Within the aperture in the disc and pressed over at e (Figure 3) so that the surfaces f f are forced outwards'and so firmly clamp the collet to the disc Without, however, damaging the surface g at the aperture of the disc.

The collet is screwed to the spindle j atzJ as indicated and it will be appreciated that the spaces c between the spokes provide openings through which air may escape during the filling of the mercury bath with mercury.

I prefer to construct the collet spider of substantially non-magnetic iron or steel Which thus does not become amalgamated in the mercury bath.

Having now ydescribed my invention, what I claim as new and desire to secure by Letters Patent is l. A method of forming the disc rotors of vmercury bath electricity meters which consists in providing a metal disc at its centre with an aperture and adjacent such aperture and adjacent the periphery providing it with tapered surfaces, applying a metal protective coating to said disc and applying pressure to `said disc, thereby hardening it and planishing its surface and incidentally rendering its thickness substantially uniform t-l1rou,f rhout` Q. A mounting for the disc rotor of an electricity meter Aincluding a spindle, a collet rigid therewith, a disc-like annulus, the inner periphery of which is convex in any plane containing the longitudinal axis of the annulus, and a plurality of spokes embodied in said collet, the outer surfaces of which spokes are concave in cross section to correspond with the said convex inner annulus periphery when clinched into position'within the annulus.

3. A mounting for the disc rotor of an eleotrioityrmtel including a spindle, a collot spond with the sniflconvex inner annulus pe- SCreWecl to saiclgpinclle, a disc-like alumnus,- ripliery When clinched into position within the inner' perphary of which is convex in any the annulus.

plane containing the longitudinal axis 0l the In testimony whereof I have signed myV 5 annulus, and L plurality of spokes embodied naine Vto this specification.

in said collet, the outer surfaces of which spokes are concave in cross section to coiife- SEBASTIAN ZIANI DE FERRANTI. 

